BIOSTATS LEC - 01

Horizontal scale:
Vertical Scale:

Histogram

1. classes of quantitative data values (class boundaries)

2.represents frequencies

Horizontal scale:
Vertical Scale:

Relative frequency histogram

1. class boundaries

2. relative frequencies (percentage)

NORMAL (Bell-shape) DISTRIBUTION

UNIFORM DISTRIBUTION

Skewed to the right (positively)

Skewed to the left (negatively skewed)

NORMAL QUANTILE PLOT (Normal Distribution)

NORMAL QUANTILE PLOT (Not Normal Distribution)

NORMAL QUANTILE PLOT (Not Normal Distribution)

Dotplot

Bar graphs

Pareto charts

(1) The smallest stem in the data set is

(2) second stem

(3) vertical bar

(4) leaves
(5) w/ underline

Stem-and-leaf plots

(1) displayed in the upper left-hand corner of the plot.

(2) equals the first stem + 1 is displayed, below the first stem.

(3) found to the right of the column of stems

(4) displayed to the right of the vertical bar

(5) decimal point

Time-series graph

Pie chart

X =
Y =

Frequency polygon

• class midpoint

• frequency

RELATIVE FREQUENCY POLYGON

Lines below =

Lines above =

Lowest line of the box =

Highest line of the box =

Blue line inside the box =

Box plot

• minimum value of the data

• maximum value of the data

• Lower quartile

• upper quartile

• median

can be use in some like

Nonzero vertical axis

• Scatterplot bc we’re not comparing, but finding relationship

Problem

Pictographs

• Different years, different populations = not comparable

• Percent shouldn’t be used, real figures dapat

Scatterplot/diagram: Correlation

Scatterplot/diagram: No Correlation

Regression equation / line

Cochran sample size formula

MODIFICATION FOR COCHRAN'S FORMULA IN SMALLER POPULATIONS

FINDING SAMPLE SIZE WITH KNOWN POPULATION STANDARD DEVIATION